(i) Field of the Invention
This invention relates to the continuous production of positive and negative electrode plates for use in lead-acid batteries, and more particularly, is directed to elimination of paper as barriers on both sides of pasted continuously expanded, punched or cast metal mesh strip during production of battery plates. Heretofore, such paper has been a standard requirement in the continuous production of battery plates in order to avoid the sticking of paste to the dies in the apparatus used to cut pasted metal mesh strip into battery plates.
(ii) Description of the Related Art
Conventional book mold cast plates for use in lead-acid batteries do not need a paper barrier because the individual plates do not require cutting after pasting. However, the continuous production of battery plates by the cutting of individual plates from rotary or reciprocated expanded mesh or cast mesh strip saturated with a paste necessitates the presence of a paper barrier on each side of the mesh strip to cover the paste.
U.S. Pat. No. 4,315,356 granted Feb. 16, 1982 to Cominco Ltd. discloses the production of expanded metal mesh from a coil of continuously cast metal alloys for use as battery plates. A slitting and expanding technique was developed for the continuous production of the expanded metal mesh from lead alloy strip cast by a drum caster. The expanded metal mesh was coated with a paste and the pasted mesh divided into discrete plates by a plate-cutter apparatus. Related technology is typified in U.S. Pat. Nos. 4,315,356 issued Feb. 16, 1982, No. 4,291,443 issued Sep. 29, 1981, No. 4,297,866 issued Nov. 3, 1981, No. 5,462,109 issued Oct. 31, 1995, and No. 5,896,635 issued Apr. 27, 1999 to Cominco Ltd., and in U.S. Pat. No. 5,669,754 issued Sep. 23, 1997 to Advanced Dynamics Corporation Ltd., all incorporated herein by reference.
The plate-cutter apparatus, also known as a divider or die-cutter, is an integral part of the continuous lead-acid battery manufacturing process and is well known in the art. The plate cutter is located immediately after the stage for application of paste to the lead mesh. Conventionally, a paper barrier is applied onto the paste on both sides of the lead or lead alloy mesh strip. This paste, without the application of a paper barrier thereto, would stick to the tooling of the plate cutter, quickly leading to improper cuts causing production downtimed. In addition, randomly deposited excess paste results in battery cell assembly problems. The use of these paper barriers adds significant material cost to the battery and creates numerous production problems. Paper tearing and paper release from plates cause major production line downtime. In addition, plates that are rejected during the production process, and recycled in the battery plant, can cause fires in plant bag houses because of the flammable paper overlay.
There have been many attempts to eliminate the presence of the paper barrier in continuous mesh cutting processes. For example, special die coatings and non-organic release agents have been tried, without success. The use of a paper overlay for battery plates began in the mid of 1970's and all efforts since then to eliminate its use have failed. As a result, the presence of a paper barrier has been a requisite in the continuous production of battery plates from strip and literally billions of battery plates have been produced and continue to be produced using the paper barrier system.